this piece according to the description, dates to c.1830s and is French - so a French 'Etruscan style' design piece, with orange enamel and gilding and on a 'milchglas' base glass item:
http://www.proantic.com/display.php?mode=obj&id=181053 Although there are differences on this underplate of this piece in terms of the base, I can also see similarities.
Also, athough unconnected in terms of type of glass and design, I have found a flacon eau de Melisse which, I believe from similar items,dates to the 1820's and has similar 'gothic' design pattern on it:
http://www.anticstore.com/flacon-eau-melisse-opaline-monture-neogothique-bronze-dore-epoque-charles-x-46324PSo I suspect, from all these examples given in my last few posts,that I'm correct about my plate dating to quite a bit earlier than mid 1800s ... dates looking most likely perhaps around 1820s although it could be earlier.
re the angel - I've come across one glass (French), that has a facial depiction on it that looks so similar to the face on the angel it made me stop and look again. However, this may be an artistic 'style' rather than a similar period of course. That dates to late 18thc.
Apart from that, the only observation is the way her hair is curled back around her face and I've only seen that on Russian angels.
Caveat - this is just an update, my searches are not 'exhaustive'. Any further information or updates welcomed

m